Method for reducing the viscosity of aralkyl ethers of cellulose



Patented Oct. 19, 1937 U I "S AT-E .4 a Y i2,096,1141 a, a

, 'rm'rnonron REDUCING rim vlscosrry: f. T

OFABALKYLETHERS F CELLULOYSE 1 Eugene J, Lorand, Wilmington, Deli, assignor't o .Hercules Powder Company, -Wilmington, -Del.,

v acorporation of Delaware 4 1 IQJ o nrawiiigf-ApmicatibnM y 5 1934, 1

sierial No. 'l24,2 06 I i 17 Claims. (01. 260-152) This invention relates to a method for reducing i the viscosity of aralkyl ethers ,oi cellulose, as, for, .example, benzyl cellulose, xylylcellulose or'xylyl ether of cellulose, beta-phenyl-ethyl ether, of v v used and the degree ofviscosity drop desired. 5 Heretofore low viscosity aralkyl celluloses have 5, cellulose, etc.

been obtained in various ways "as, for example, by the proper choice andtreatment of the raw mate-- rials and by conducting the'aralkylation of the. @Qcellulosic material under conditions favoring a depolymer'ization '01 the cellulose molecule,

, Again, it has been suggested to reduce the viscosity of benzyl celluloses by digestion with water and steam under pressure in the presence o f a g benzyl halidejas benzyl chloride, Such procedure, however, is undesirableiorivarious rea- 'sons among 'which are that mostof the benzyl chloride used in the benzylation must be removed by vacuum distillation thesizeof the apparatus lo'must bev greatlyincreased to take up the large- .amount of water and steam and the further han-,

dling of, the resultantpasty product is diflicult.

, Nowfin accordance with this 'in'ventionQit has been .i'oundthat the viscosity of arallryl cellulose can be reduced by treatmentat "anjelevated' tem- .perature with a benzyl halide alone, i.e.;without theuseof water or steam. The aralkyl halide may, 'for "example, be benzyl chlorideuxylyl chloride, beta-phenyl-ethyl chloride, etc. T e treata f ment may be applied 'onco'mpletion of the, aralkylation or asfa subsequent procedure.

Gene'rally'speak'ing,.themethod in accordance with this invention is adaptable for, reducing the ether it will be noted thatireduction 'in viscosity I or the aralkyl cellulose willbe inhibitedyb y thef I viscosity of aralkyl cellulose ,ethers produced, for example, by the action of ben'zyl chloride or one of its homologues on'alkalijcellulose.

"In carrying this invention into practice, for example, the treatment for viscosity reduction; n v

polymerizing effect of thearalkyl lialid may beapplied to "an .aralkyl' cellulose after its 40 production, or in the course of its production,

Thus, by way of, example, a solution of aralkyl cellulose, as, for example, benzyl cellulose, in an, aralkyl halide, as,'for example, benzyl chloride,

f is subjected to an elevated temperature for such period as is necessaryto effect the desired viscosity reduction,

I The solution of aralkyl cellulos e in an aralkyl} halide maybe 01' any'desired concentration. Generally speaking a concentration within about the '50 range 5, 130% will be found satisfactory, while mass due to the fact that tliei esidua caustic cellulose 'in solution in anexce ss oi;ar alkyl;fha lide I i V f ulate thebenzyl cellulose, produced by; the usual, f 5]; wide limits will determine the time required to ,eral, temperatures withingsay about "the range 100 C will be found desirableland thelpriod of treatment will depend uponYthetempeifature As ,more' specifically illustrative, for example, a 10% solution of benzylcellulose'may .beused.

- The viscosity of the solution on heatingior six hours at 0., assuming it have had an initialviscosity of 1555 centip oiseslas measuredwith a horizontal capillary viscosimeter, cwill beifound V to have been reduced to'about 116 centipoises In carryi'ngthis invention into practice, as; has v been indicated, the, treatment for reducing .vis

cosity may be included asia part of thelprepara- 15 J tion of; the ether. 1 In soproceeding, it has been found necessary 'togeliminate the protective action on the cellulose ethe'r of causticalkali remaining in the reaction mass on completion ofthearal;

kylation, Hence, on completion'lof the aralkyla 201. 1 tion the alkali content'ofl-the mass is. determined, by any suitable methodand anarnountof alkalibinding agent such a an acid orl an acid salt, as,

for example, acid sodium sulphate, 'mono'basic sodium pho'sphate,.oxalic acid, etcQis added and-"25 f the mass'containing usuallygabo'ut- 151% ofaralkyl cellulose in. solution, in the excess ,of, aralkyl l halid'e'normally used in aralkylation is thenheated in .an oil bath withfvigo'rous stirringior such,

time as is required tojefiect the desiredvisco'sity f m reduction. j U

Incarrying out the methodin, accordanc tan this invention, as a part of the preparation offthe presence of residual caustic alkalijin 'theTreaction alkali protects the cellulose ether i'ro consequence the use of an .all-jralifbinding' com 0 pound, such as an acid or an acid saItJs-Jneces-Q cess of alkali binding compoundas for; ample, Y more than excessais requiredinlorder'to obtain viscosity reduction on subsequent heating 5 treatment of alkali cellulose with-entices 5 551* 1 chloride. Hardening oi themassishel by maceration with two glass rods.v when the sample is suillciently broken p, t e whole is washed'over with 100-450 cc. water and*'10.,cc.'

half-normal hydrochloric acid added. After} to"10,.minutes theexcess acid is back-titrated with.half norri a.lsodlurnhydroxide solution inv 4 benzyl chloride, addingsto the reaction mass, an I alkali binding compound in amount V V in excess oi that theoretically necessary tofneuj traliseresidual alkali mass and.

heatinsc'the reaction 4 The method of producing thepresence e: methyl orange, asan'indicator.

iscalculated in the usual Assuming that the reaction mass result theslkalicontentoi the massthe; treated for reduction of the viscosity or the benwl 'oellu loseaamounts to 200 grand contains 2,4 zrotfrcaustic-alkali, there ls;caddedto the,mass.ahouttreatment in'* accordance ensured in a nleneot the aralblation-process and recovery of tion the product or; been indlcatedgas apart, ofthepreparation or the ether aite'reompl'e'tionf of the aralbli tion but before nwm be' ppreciated that this "llc'ationoithebroduct.

' nerature',;time, orconcentratiou' o1 solutionLnor isthis invention tonbe' limited by details of prov cglure, ,timeand temperature given herein for" oi'lllustration n clarification e: the e invention.

wnst'rem siidu s 'rete nvotect byLettei-s -ratent'isz; a 1 41. The. method 01910611612181 low, viscosity *1 me nu o' e; which'lncludes aralky'lat'lngian alkali' cellulo'sein the, Dresenceoi an excess of an heating the reaction mass.

alkali cellulose in the presence-oi an excess of an aralbl halide, adding to thereaction an ,alkali bindlng compound inar'no'unt more than 100% inexcess' e: that theoretically necessary to neutralize re'sidualalhali in thereaction and y "heatl k h ir betionmass;

,3. Thef method oflproducin's alowfuiscosity H t e,

{aralkyl halide in the substantial absence or 'benzyl cellulose, which includes benflla'tlngen 7 cellulose in the presence of an escessol' er thef e 'fthe i-eawtion mass.

ppree i'ated thatt'hemethod* may be ppl ied toaralkyl' cellulose aiter-;complel velltiillils not depmfdent upon the use oi; anyparticulajr tem'-' od of 'producln gja low viscositi aralkyl cellulose, which includes aralkylating an inimount substan' tially 1o! that; I retically necessary to in the reaction be'nzyl cellulose," which'includesbenzylatintj'anf I alkalij cellulose in the'-pres'enceotran benzyl chloride',iaddins'to* sulfate inamoun cess otthat theoretic H I J residual alkaliin the mmtin y s e w e lulose in solution in aralkyl halide, the solution on aqueou's orsubstantially'nom' -a. meth doixprodwnsalow vieeositr ben'zyl cellulose, which alkali cellulose in the 1 9 9 141 1. ml o b j o m h s tially in excess bfthat thee neutralize "residual in and heating the reaction v ;"--9."lhe niethodoiflprodl a w benzyljcellulose, which includes alhalijcellulose in the presence chloride, addinggto ithereaction =50 oxalic acid in amountsubstantially; in excessot that theoretically necessary.to neutraliseresidual alkali in the reaction in action mass.

10. Themethod "or adii aralkyl cellulose in solutionin an in the substantial absence ot water j u 11.'The method oi reducing the viscosit of} .benzi'l cellulose, which ineiuae lheatihs cellulose in solution; injbenzyl fYthe" substantial absence. oliwa ter'. a

'12."l.he method or; I h j wwts of an arallgyl cellulose. which includes anaralkyl cellulosein solutlo in '4 :under acid-condition;

ibenzyl' cellulose, which; includes pheatins cellulose insolution in ,benayl chloride under acid conditions... I j t f 17o 14.1'I'he method ot'reduci'ngthe an aralkyl cellulose. which, includes heating. a 5%-30% solution of an aralky1'cellulose1lnj,;an

, 15. The method or reducins thevlscosityoif an 75 enw stinsigenviw ot anwenceqof v,

V v ;',the oi: as "an aralkyl" cellulose, whiehincludesheatihgg an aralkylhalide as: 13. The method oilred'ucin er 1'1. The methodjof. reducing Yule, viscosity of: v henzyl cellulose, which includes heating. benzyl cellulose in solution in benzyl chloride in the aralkyl' cellulose, which includes heating an aralkyl cellulose in solution in; an aralkyl halide. in the substantial absence of water at a temvperature of from about to about 100 C.

16. The method of reducing the viscosity of an aralkyl cellulose, which includes heating an aralkyl cellulose in'solution in an aralkyl halide under acid conditions at a temperature of 1mm about 50 about C.

stantial absence of water at a temperature of about C. for about 2-3 hours. 1

s a h I 

